Drilling for hydrocarbons provides many challenges to operators that must be overcome, including, but not limited to, adverse field conditions. To that end, drilling for hydrocarbons can be cost intensive and complicated according to the size of the hydrocarbon field encountered, the overburden characterization and other similar issues.
Many times, formation conditions are measured by a downhole tool. Afterward it is desired to transmit the measured parameters from the downhole environment to an uphole environment. There are different methodologies that can be used to transmit signals from the downhole environment to an uphole environment. One such method is a wireline measurement system. Wireline measurement systems may be used to transmit information between two locations. Such wireline measurement systems have the distinct disadvantage, however, of requiring the cessation of drilling and often the removal of downhole components before the wireline apparatus may be inserted into the wellbore. While wireline measurement systems may be accurate in the characterization of data downhole, significant problems remain with such systems. As drilling must be discontinued to allow the wireline tool to be inserted, drillers lose valuable drilling time where they make measurements with wireline tools. Drillers are interested in methods and systems that prevent the need for drilling stoppage, thereby increasing profitability of field operations.
One such method to increase the profitablility of field operations is a measure while drilling (“MWD”) technology called mud pulse telemetry. Drilling fluid, commonly known as “mud” is used to lubricate and cool downhole drillstring components. Mud pulse telemetry uses coded drilling fluid pressure pulses that are generated downhole to follow the “mud flow” path to the uphole arrangement. Pressure signals sent from downhole travel uphole are detected by an uphole arrangement and decoded. Using this technology, drillers are capable of measuring formation features and subsequently capable of transferring this information to the uphole environment during the drilling process, greatly increasing profitability. Specifically, mud pulse telemetry may be used to transmit data related to measured formation temperature, pressure and other values that are of value to drillers.
Transmitting the data obtained from downhole tool measurements using mud pulse telemetry, however, can be a complicated operation. Conventional apparatus have a capability of transmitting information at approximately twelve (12) bits per second. Conventional apparatus have problems associated with signal strength, erosion and pressure drop across the tool used to send the signals from the downhole environment.
Conventional apparatus (using mud pulse telemetry technology) also have a very distinct disadvantage using mud pulse telemetry technology. Conventional mud pulse telemetry technology uses a series of pressure spikes, created downhole, to send information from the downhole environment to the uphole environment. These pressure spikes, however, can lead to premature mud pump failure as the mud pumps are stressed from a period of relatively low fluid friction to a very high fluid friction state. Information may be transferred from point to point, but the systems used to accomplish this task go through repetitive cycles of overpressurization. This overpressurization leads to stress and eventual failure of the mud pumps, potentially damaging further equipment, such as expensive drill bits and downhole tools. Conventional systems may also overstress the formation going from a low pressure condition to a high pressure condition.
There is a need to provide systems and methods that allow for mud pulse telemetry from a downhole environment to an uphole environment superior to the conventionally used technologies.